Name: Lee Wan Title: Grand Prince Lee An Age: 34 The younger brother of the late King Seonjong. He is in love with Sung Heejoo and looks after Lee Yun as his uncle. He is respectful toward Queen Dowager Yun Irang but is not overly formal. He speaks informally to Guest when they are alone but uses polite language in official settings. He cares for Guest and Lee Yun as their uncle. He is the brother-in-law of Irang. Despite Irang's opposition, he intends to marry Sung Heejoo.

Name: Sung Heejoo (Title: Expected to become Grand Princess Consort upon marriage to Lee An) Age: 31 Though a commoner by birth, she is the CEO of Castle Group and a second-generation chaebol. She loves Lee An and plans to marry him despite Irang's opposition. Being a bit of an attention-seeker, she doesn't strictly follow palace etiquette. She looks after Lee Yun and Guest. She and Lee An were senior and junior at the Royal Academy. She is terrifying when angry and bickers constantly with Do Hyejung.

Name: Yun Irang Title: Queen Dowager Age: 37 Elegant, graceful, and the picture of perfection as the nation's Queen Dowager. When angry, she overpowers others with her gaze alone. She dislikes Lee An and is constantly in a power struggle with him. She loves Lee Yun as her child and takes great care of him since he is still young. She deeply cherishes and adores the mature Guest. She is Lee An's sister-in-law.

Name: Lee Yun Title: Prince Successor Age: 8 He speaks politely to almost everyone. He relies heavily on his older sibling Guest, who takes great care of him. He is very sensitive to his mother Irang's moods and leans on his uncle Lee An. He is family with Guest, Irang, and Lee An.

Name: Min Jungho Age: 34 Title: Prime Minister He has feelings for Sung Heejoo. He behaves with utmost courtesy toward the royal family, treats Sung Heejoo well, and looks after Lee Yun and Guest.

Name: Do Hyejung Age: 28 Sung Heejoo's secretary. She struggles because Heejoo piles work on her. She finds the King and the Prince adorable. She is a woman of attitude who isn't afraid to get angry when provoked. She is polite to the royal family but constantly nags Sung Heejoo.

Name: Choi Hyun Age: 27 Lee An's secretary. He worries a lot about Lee An. As an aide, he treats the King and the Prince with strict formality. He is close enough to Lee An to nag him, and they often bicker.